Polyaniline is a polymer that has been explored as an organic conducting material. It is relatively inexpensive, it can be readily synthesized via chemical or electrochemical methods and it is environmentally stable. As a conducting polymer, polyaniline has found use in the microelectronic industry, photovoltaics, batteries, fuel cells and sensors. Other attractive fields for utilization of polyaniline include anti-statics, electrostatic dissipation (ESD) coatings, electromagnetic interference (EMI) shielding, anti-corrosive coatings, hole injection layers, transport conductors, ITO replacements, actuators and electrochromic coatings.
Polyaniline is synthesized from aniline and can be found in one of three oxidation states: leucoemeraldine; emeraldine; and (per)nigraniline. Processing polyaniline from aniline monomer presents some difficulty as it is a rather insoluble crosslinked powder that does not readily melt. One synthesis is developed that uses an emulsion technique to produce a final product in a castable form in a solvent (e.g., toluene, xylene, hexane, etc.) so that polyaniline can be made into films. One reproducible synthesis of this form utilizes dodecylbenzene sulfonic acid (DBSA) as the dopant, because DBSA acts not only as a dopant but also as an emulsifying agent.
Drawbacks to the DBSA approach are that DBSA generally does not provide high conductivity and a process to separate out excess dopant to achieve a relatively pure product is often tedious and time consuming.